1. Field of the Invention
The present invention is directed toward beltless conveyors and, more specifically, to an electric shaker conveyor assembly.
2. Description of the Related Art
Conveyors are well known material handling devices that have application in a wide variety of environments for transporting objects from one place to another. For example, one type of conveyor employs a belt formed into an endless loop which is entrained about at least a pair of rollers spaced apart from one another and usually located at the opposed marginal ends of the conveyor. The rollers have sprockets at either end thereof. The spaced rollers are interconnected by a pair of chains entrained about the sprockets at either end of the rollers. An electric or hydraulic motor is usually employed to power the sprockets and continuously moves the belt over a substantial length of the conveyor between the rollers. In this way, objects may be transported by the conveyor over its length.
Conveyors often find applications in manufacturing environments. For example, in metal stamping operations, conveyors are employed to move parts between successive presses or from a press into a bin. In addition, conveyors are used for inspecting, transporting and assembly situations and can assist in maximizing production by removing parts, slugs or other scrap and materials from under low clearance areas like punch press dies and permitting continuous operation of the press. However, belted conveyors suffer from the disadvantage that the belts are often cut by the sharp edges of the metal parts formed in stamping operations. The useful life of the belts are reduced and the belts must be replaced more frequently. Frequent belt replacement increases the maintenance costs of the stamping operation. Further, stamped parts and other debris may pass through the damaged belts and jam or foul the inner workings of the conveyor drive system.
In part to avoid these problems, beltless conveyors are often employed in certain manufacturing operations. One type of beltless conveyor known in the related art moves items along the length of a conveyor by a physical reciprocating action. The material to be moved is transported in or on a table, channel, or trough. The reciprocating action of the conveyor is faster in one linear direction than the other thereby causing the material to be moved with each forward stroke of the conveyor. The inherent reciprocating action of these types of beltless conveyers causes them to be generally referred to as shaker conveyors. Shaker conveyors do not suffer from cuts or worn belts and thus have been adopted in numerous manufacturing environments.
A shaker conveyor may even be used to transfer corrosive, high-temperature, heavy, or other difficult to transport materials from place to place. For example, hot metal castings, particulate material, or other material difficult to transport due to physical or chemical characteristics can be transported by a shaker conveyor. The flexibility as to different types of materials is derived from the conveyor table or trough, which supports the material being carried. The shaker table can be made of materials resistant to heat, corrosion, or physical or chemical problems caused by the items being conveyed.
As previously mentioned, to convey the items or material on the table, the shaker table may be accelerated in the direction of a desired material movement to reach a maximum forward velocity and then the direction of movement of the table may be rapidly reversed so that the material slides along the table in the desired direction. As the table moves in the reverse direction, the material decelerates and comes to rest, and is then subject to the next reciprocal forward movement of the table so that there is little or no backward sliding of material being conveyed. In this manner, during one of the reciprocal movements, or strokes, the table provides a griping action on the material being conveyed. Conversely, the table provides a sliding action on the material being conveyed during the opposite reciprocal movement.
There are a number of conventional prior art shaker mechanisms that achieve the desired result of a forward motion of material by using a reciprocating action. These conventional shaker conveyors may employ crankshafts or other eccentrics with linkage arms to achieve the desired reciprocal motion, often with heavy flywheels. The linkage arms are pivotably attached to the flywheel or eccentric at one end and are likewise pivotably attached to the shaker table at the one ends. By the inherent physical differences designed into the linkage arms or the placement of their attachment points, or through the use of other mechanical systems, the reverse movement of the shaker table may be faster than the forward movement. While these types of drive mechanisms provide satisfactory reciprocal motion, they typically require a number of operating elements and linkages some of which can be relatively complex, and tend to be difficult to manufacture. These complex shaker assemblies can also be relatively expensive to manufacture and maintain. More specifically, the complex drive systems raise the cost of the shaker conveyor of this type. Furthermore, the linkage arms used to provide the reciprocating motion have a tendency to get out of line, reducing the efficiency of the shaker and causing further operational problems.
Thus, there remains a need in the art for a cost-effective electric shaker conveyor that converts rotary motion of the drive engine into repeated rectilinear motion to the conveyor using an elegantly simple, effective mechanical actuation. Moreover, there remains a need in the art for such a conveyor that is relatively quiet and maintenance free. In addition, there remains a need in the art for such a conveyor that may incorporate these features in a lightweight and compact design such that it may be relatively portable and may be easily employed in any number of relevant applications.